1. Field of the Invention
The present invention relates to a sealing device in accordance with a sealing technique, and more particularly to a sealing device which is suitably used in a high-pressure hydrogen piping for a fuel battery. Further, the sealing device in accordance with the present invention is also used in the other high-pressure gas piping such as a piping for a helium, a nitrogen or the like.
2. Description of the Conventional Art
Conventionally, a sealing device 51 shown in FIG. 6 has been known. In this sealing device 51, a seal ring 52 constituted by a rubber-like elastic body is installed to an installation groove 54, and a backup ring 53 made of a material which is hard to transmit gas is installed to a low-pressure side (refer to patent document 1).
However, in the case that the backup ring 53 is made of the material which is hard to transmit gas, there is a case that hardness of this material becomes extremely higher in comparison with the rubber-like elastic body corresponding to a material of the seal ring 52. In this case, if the sealing device 51 mentioned above is used, for example, in a position where a pressure alternation (ON and OFF) is generated under a high pressure condition, the seal ring 53 is damaged by the backup ring 54 made of the hard material, whereby there is a risk that a sealing performance is deteriorated.
Further, in the following patent document 2, there is described a sealing device in which a low-pressure side of a seal ring is provided with a second backup ring made of a soft material and a first backup ring made of a hard material, an inner-diameter taper portion is provided in a peripheral surface close to a groove bottom of the second backup ring, and a taper-shaped bottom wall portion corresponding to the inner-diameter taper portion of the second backup ring is provided in a groove bottom surface of a mounting groove, in order to improve a sealing performance and a durability. However, this sealing device is used for another intended use, and does not correspond to a seal for gas.
Patent Document 1: Japanese Unexamined Patent Publication No. 2001-355733
Patent Document 2: Japanese Unexamined Patent Publication No. 11-72162